message_connect()
Create a connection to a channel
Synopsis:
#include <sys/iofunc.h> #include <sys/dispatch.h> int message_connect( dispatch_t * dpp, int flags );
Arguments:
- dpp
- The dispatch handle, as returned by dispatch_create() .
- flags
- Currently, the following flag is defined in
<sys/dispatch.h>:
- MSG_FLAG_SIDE_CHANNEL — request the connection ID be returned from a different space. This ID will be greater than any valid file descriptor. Once created there's no difference in the use of the messaging primitives on these IDs.
Library:
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
Description:
The message_connect() function creates a connection to the channel used by dispatch handle dpp. This function calls the ConnectAttach() kernel call. To detach the connection ID, you can call ConnectDetach() .
Returns:
A connection ID used by the message primitives, or -1 if an error occurs (errno is set).
Errors:
- EAGAIN
- All kernel connection objects are in use.
- EINVAL
- Dispatch dpp doesn't have a channel.
Examples:
#include <sys/dispatch.h> #include <time.h> #include <stdio.h> #include <stdlib.h> int main( int argc, char **argv ) { dispatch_t *dpp; int flags, coid, id; if( ( dpp = dispatch_create() ) == NULL ) { fprintf( stderr, "%s: Unable to allocate dispatch context.\n", argv[0] ); return EXIT_FAILURE; } id = resmgr_attach ( … ); … if ( (coid = message_connect ( dpp, flags )) == -1 ) { fprintf ( stderr, "Failed to create connection \ to channel used by dispatch.\n"); return 1; } /* else connection to channel used by dispatch is created */ … }
For examples using the dispatch interface, see dispatch_create() , message_attach() , resmgr_attach() , and thread_pool_create() .
Classification:
Safety: | |
---|---|
Cancellation point | Yes |
Interrupt handler | No |
Signal handler | No |
Thread | Yes |
Caveats:
Dispatch dpp must block on messages.